Hoist



B. F. SCHMIDT HOISTl April 2 5, 19,50

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Patented Apr. 25,m 1950 UNITED STATES PATENT OFFICE Divided and this application December 15, 1945, Serial N0. 635,257

K 8Claims. 1

My invention relates to a hoisting mechanism andhas particular reference to a geared chain hoist employing' an improved reduction gearing.

This application isa division of my copending application Serial No. 548,517, led August 8, 1944, and entitled Reduction gearing.

In many industrial applications it is desirable to provide hoisting mechanisms which provide a relatively great mechanical'advantage to permit very large loads to be lifted by the application of relatively small forces. It is the common practice to use gearedchain hoists for this purpose, but because of the `high v,gearratio between the driving chain or driving motor .and the hoisting chain, it is impossible to rapidly raise or lower the hook Whenno load is suspended therefrom. This results in a considerable loss of time in many instances, particularlyv in those cases Where it is necessary to lower the-hook through a large distance before it `may be attached to the object to be lifted.

It is therefore an object of my invention to providev a hoisting mechanism which overcomes the above noted disadvantages by providing for a rapidmovement of the hoisting chain until a load is imposed thereon and which includes automatically introducing a gear reduction between the driving source and thel hoisting chain responsive to the application of a load to thehoisting chain.

It is also an object of my invention to provide a, hoisting mechanism. of the character set forth in the preceding paragraph which includes means for selectively introducing a fixed gear reduction between the driving source and the hoisting chain.

It is also an objectof my invention to provide a hoisting mechanism of the Vcharacter set forth in the preceding paragraph which includes a gear reduction unit` of improved construction which may be readily and simply manufactured.

Other objects and advantages of my invention will be apparent from a study of the following specifications, readA in connection with the accompanying drawing,l wherein:

Fig. l is a vertical sectional View of a chain hoistmechanism constructed-in accordance with the preferred embodiment of my invention;

Fig. 2 is a cross-sectional view taken substantially along. the line II-II of Fig. 1; and

Fig.. 3- isv a detail. view of kone of the transmis'- sion .pinions which. I employ in the reduction gearing forming apart' ofy the hoisting mechanism.

Referring to the drawings; I` have illustrated as an example of the hoisting mechanism of my' invention a chain hoist including a supporting hook I which engages a yoke-like frame 2. The' frame 2 has a transverse bore 3 formed therein within which is mounted a pinion supporting frame 4. The frame 4 is provided with a longi-y tudinal bore E, i-n opposite ends 0f which are placed bearings t and I used to rotatably supporta power shaft `8. The power shaft 8 i'nclude's an outwardly extending portion 9 to which is secured a pulley I0 provided with chain' sprocket recesses H to receive a, driving chain 2. Alternatively, in place of the pulley I0 and driving chain I2, an electric motor or other type o`f power source'may be coupled to the shaft extension Sl for driving the power shaft 8.

The power shaft 8 is provided with a worm thread i3 which meshes with a pair of oppositely positioned pinions or worm gears I4 and I 5. The' pinions I 4 and I 5 are mounted as by means of needle bearings I 6 upon stub shafts I'I and i8 fitted into transversely extending shaft-receiving bores i8 and 20 formed in the pinion supporting frame 4. The shafts Il and I8 may be retained in their respective bores by means of cross pins' 2i and 252 as shown in Fig. 2.

The pinions i4 and I5 are received within recesses 23 and 2li cut into the pinion frameor carrier 4 as shown in Figs. 1 and 2. End thrust on the pi-nions may be taken by thrust bearings 25 and 2S encircling the stub shafts IT and i8 and interposed between the ends of the pinions I4 and i5 and the pinion carrier 4.

Each of the pinions I4 and I5 isr preferablyv constructed along the lines shown in Fig. 3 and includes a worm wheel portion 21 adaptedA to mesh with the worm thread I3 and including a worm thread portion 28. The worm thread portion 28 is preferably of conical form and adapted to mesh, as shown in Fig. 2, with internal type worm wheel teeth 29 formed upon an outer driven member Sii. The outer driven member 31@ is, according to the preferred embodiment of my in vention, formed as a chain sprocket including chain guiding anges 3| defining chain link pockets 32 for drive-bly engaging a hoisting chain 33. The driven member 30 is mounted for rotation relative to the pinion carrier 4 as by means of ball: or roller bearings 34 and 35 interposed between the carrier 4 and the driven member Si).

It willbe seen that if the pinion carrier 4' is heldY against rotation relative tothe' yoke 2, rotation by any suitable means of the power shaft' 8 will cause rotation of the pinions'V I4 yand I5" at a. greatiy reduced speed. It will 4be fertilit#7 2,505,435 I 'l i i more seen that because of the engagement of the worm threads 28 of these pinions with the worm gear teeth 29, the driven member 30 will be caused to rotate at a still further reduced speed. Because of the high gear ratios between the worm thread I3 and the worm gear portions 21 of the pinions I4 and l5 and because of the high gear ratio between the worm threads 28 and worm gear teeth 29, it will be seen that a tremendous mechanical advantage is obtained between the power shaft 8 and the hoisting chain 33.

In order to permit the ready and rapid movement of the hoisting hook (not shown) understood to be connected at the end of the hoisting chain 33, I prefer to provide a means for selectively permitting rotation of the pinion supporting frame 4. This may be readily accomplished by providing a pin 36 slidable through a vertically extending opening 31 provided in one of the legs of the yoke 2, the upper end of the pin 36 being adapted to enter a radially extending socket 38 formed in the frame 4. The pin 36 is normally urged upwardly by means of a spring 39 but may be withdrawn Whenever it is desired by means of a chain or pull cord 40.

Thus if the pin 36 is disengaged from the socket 38 and the pulley I9 is rotated, the relative friction between the parts will cause the driven member 30 to be rotated at the same speed as the power shaft 8 until a load is placed upon the hoisting chain 33. When this occurs the hoisting chain becomes taut with relation to the load that is to be hoisted and release of the pull chain 4i) will permit the pin 36 to be urged by the spring 39 upwardly against the surface of the pinion frame 4. Thereafter rotation of the power shaft 8 will cause the frame 4 to rotate within the bore 3 until the pocket 38 is realigned with the pin 36, at which time the pin 36 re-enters the socket 38. This locks the pinion carrier or frame 4 and the yoke 2 against relative rotation so that further rotation of the power shaft 8 will cause rotation of the driven member 39 at the reduced speed and with the mechanical advantage necessary to lift the load.

If desired, a chain guard 4! may be mounted upon the yoke frame 2 as by means of screws or bolts 42, the guard preferably being formed with a portion 43 extending immediately above the periphery of the pulley I8 so as to prevent the chain i2 from being inadvertently removed therefrom. The guard 4l preferably also includes an extending arm portion 44 which is extended across the yoke immediately above the periphery of the chain sprocket 36-32 to perform a similar function for this sprocket.

From the foregoing it will be observed that I have provided a hoisting mechanism of the gear reduction type which includes means for moving the hoisting chain and hook attached thereto at a rapid rate of Speed until a load is placed thereon, and that by virtue of internal friction the device operates to automatically interpose a variable gear reduction until the load equals the friction, and that by virtue of the spring 39 and pin 36, the device may be operated to interpose a fixed ratio reduction gearing between the driving chain and theV hoisting chain.

It will also be noted that the hoisting mechanism described employs a novel form of reduction gearing which provides in a very small space a great mechanical advantage. The reduction gearing disclosed herein is also disclosed and claimed in my aforementionedcopending application.

While I have shown and described the preferred embodiment of my invention, I do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

Iclaim: Y

1. In a hoist, a yoke frame; a pair of chain pulleys; a reduction gear unit comprising three concentrically mounted members supported by said yoke frame and comprising a shaft member having a worm thread thereon, a frame member mounted upon said shaft member for rotation relative to said shaft member upon the same axis as said shaft member, a ring gear member having internal gear teeth surrounding said frame member and rotatable relative to the frame on the same axis as said frame member, a pair of pinions rotatably mounted on said frame member at diametrically opposite sides thereof, said pinions each comprising gear teeth meshed with the worm on said shaft member and gear teeth meshed with the gear teeth on said ring gear; means rigidly mounting one of said chain pulleys upon said shaft member; means rigidly mounting the other of said pulleys upon said ring gear member; and means for selectively connecting said frame member to said yoke.

2. In a hoistja yoke frame; a pair of chain pulleys; a reduction gear unit comprising three concentrically mounted members supported by said yoke frame and comprising a shaft member having a worm thread thereon, a frame member mounted upon said shaft member for rotation relative to said shaft member upon the same axis as said shaft member, a ring gear member having internal gear teeth surrounding said frame member and rotatable relative to the frame on the same axis as said frame member, a pair of pinions rotatably mounted on said frame member at diametrically opposite sides thereof, said pinions each comprising gear teeth meshed with the worm on said shaft member and separate gear teeth meshed with the gear teeth on said ring gear; means rigidly mounting one of said chain pulleys upon said shaft member, the other of said pulleys being formed upon said ring gear member; means rotatably mounting said frame member in said yoke, said mounting of said frame member comprising a bore in said frame member; and a latch pin mounted upon said yoke for movement into and out of said bore, whereby when said pin is released from said bore the three concentric members may rotate as a unit at the same speed as said shaft member.

3. A reduction gear hoist comprising three concentric members mounted for independent rotation and including a shaft having worm threads thereon, an intermediate frame, and an outer internal gear member; a hoisting cable wheel mounted on the exterior of the internal gear member and adapted to impart a tension to a hoisting cable disposed on said wheel; a pinion carried by the intermediate frame and adapted to rotate on a non-parallel axis with respect to the members and having worm wheel teeth engaging the shaft Worm teeth and having worm teeth engaging the internal gear; a supporting yoke having a bearing formed on at least one of the members so as to support the three concentric members; a latch for selectively locking the intermediate frame to the yoke; and means for im, parting a drive to the shaft.

4. A reduction gear hoist in accordance with claim 3 wherein the pinion is mounted on an axis transverse to the axis of the members and has its worm teeth formed on a cone-shaped portion adjacent the worm.

5. In a chain hoist, a yoke having a pair of depending members, a hook for supporting said yoke, a gear carrying frame mounted in said depending members for selective rotation, a latch for selectively engaging said gear carrying frame to prevent rotation thereof, a chain wheel for a hoisting chain provided with an internal ring gear mounted for rotation on the exterior of said gear carrying frame, a shaft extending out of said gear carrying frame and having a worm gear formed thereon, a chain sprocket attached to said shaft for rotating the same, and a plu rality of worm wheels mounted on cross shafts supported in said gear carrying frame and operatively connected to said shaft, each of said worm wheels having cone-shaped worm gear extensions, said extensions operatively engaging the teeth of said internal ring gear, causing said ring gear and chain wheel for the hoisting chain to rotate about said gear carrying frame upon rotation of said shaft.

6. In a chain ho-ist, the combination of a shaft having a worm thread thereon; a frame member surrounding said shaft; a ring gear member surrounding said frame member and having internal gear teeth; a yoke for supporting said members and including a hook for supporting said yoke; means mounting said members on said yoke for relative rotation about the longitudinal axis of said shaft and mounting one of said members for rotation relative to said shaft; a pair of gears mounted for rotation on said frame member on opposite sides of said shaft, each of said gears comprising a worm wheel meshed with said worm thread and having a cone-shaped extension extending beyond said worm wheel and carrying a worm thread meshed with said internal gear teeth; a chain sprocket for a, lifting chain connected to one of said members; and releaseable means carried by said yoke for normally engaging and holding the other of said members stationary, whereby when said releaseable means is released, rotation of said shaft will drive both of said members at the same speed as said shaft, and when said releaseable means is engaged with said other member, said one member and said chain sprocket will be rotated at a predetermined but different speed relative to said shaft.

7. In a chain hoist, the combination of: a shaft having a worm thread thereon; a chain wheel for rotating said shaft; a frame member surrounding said shaft; a ring gear member surrounding said frame member and having internal gear teeth; a yoke for supporting said members and including a hook for supporting said yoke; means mounting said members on said yoke for relative rotation about the longitudinal axis of said shaft and mounting one of said members for rotation relative to said shaft; a pair of gears mounted for rotation on said frame member on opposite sides of said shaft, each of said gears comprising a worm Wheel meshed with said Worm thread and having a cone-shaped extension extending beyond said worm wheel and carrying a worm thread meshed with said internal gear teeth; a chain sprocket for a lifting chain connected to said ring gear member; and releaseable means carried by said yoke for normally engaging and holding said frame member stationary, whereby when said releaseable means is released rotation of said shaft will drive both of said members at the same speed as said shaft, and when said releaseable means is engaged with said frame member, said ring gear member and said chain sprocket will be rotated at a predetermined but different speed relative to said shaft.

6. In a chain hoist mechanism, the combination of a cylindrical gear support having a bore therethrough; an internal gear provided with a chain engaging surface about its exterior mounted for rotation around said support; a plurality of cone-shaped internal worm gears each provided with an extension upon which a helical gear is formed and mounted in said cylindrical gear support and operatively connected to said internal gear; an operating shaft mounted for rotation in said bore; a worm gear on said shaft engaging said helical gear extension; a hooked yoke support member providing bearings journaling each end of said cylindrical gear support; and a releaseable latch carried by said' yoke for normally locking said cylindrical gear support against rotation.

BENJAMIN F. SCHMIDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,125,243 Woodbridge Jan. 19, 1915 1,300,474 OConnor Apr. 15, 1919 1,555,094 Adams Sept. 29, 1925 1,661,469 Ferris Mar. 6, 1928 2,203,614 Watson July 23, 1940 FOREIGN PATENTS Number Country Date 318,326 Great Britain Sept. 5, 1929 

